Compressor shut-off valve mechanism



May 14, 1940. c. B. FlTr-s 2,200,598

COMPRESSOR SHUT-OFF VALVE MECHANISM Filed July 11, 1938 lNvEN'rolL YR/LB. F/ TES H/S' ATTORNEY.

Patented Mayu, 1940 f UNITED STATES PATENT oFFicE 'COMPRESSOR SHUT-OFFVALVE MECHANISM (lyrll B. ll'itel, Ferguson, Mo., to Wagner ElectricCorporation, i tion of Delaware St'. Louis, Mo., a corpora- AnpuontionJui,` n; ipse, sei-ini No. classi" 1 claim. (l. sta-n) My inventionrentes to valve mechanism and more particularly to shut-oi! valvemechanism ior unloading a compressor under certain conditions. The valvemechanism embodying my g ,l linvention is an improvement inthevalvemechanism shown in-the application of Fred H.

.Stroulb Serial No. 217,484, :Illed July 5, 1938.

One; of the objects of my invention'is to prq- '1 3 system associated@therewith or whenever the pressure in the receiver drops to apredetermined minimum value during a period when the fluidpressure-actuated system is notoperated. j lAnother objectof-my-invention is ,to so `conv h struct and arrange the parts of thevalve mechanism that an emcient operating valve is produced whichwillshut'oi! and open-the compressor intake at the'desired time.

other obieoto of my invention wm beooinetap-q 'al parent from thefollowingdescription taken in connection with the accompanying drawingvin which Figure 1 is a view showing my improved valve mechanismassociated with a fluid com-4 pressor and a fluid pressure-actuatedsystem; 33 and Figure 2 is a longitudinal cross-sectional view ofthevalve -mechanism showing the details thereof; and Fig. 3 is a view onthe line 3-3 of Fig. 2. n Referring to the drawing in detaiL'theeircompressor I, with which I have illustrated my shutoil' valvemechanism as being associated, is oi the rotary type having a stator 2andan eccen- .tricaliy mounted rotor 3 provided with a pluralityVofhlades l (one only being shown). The stator n has an intake port 3and an outlet port 3, the

' latter opening into an oli dome'l which is connected to a pressuretank 8 by means of a conduit 3, the dome `and tank both being consideredthe receiver of the compressor. The outlet of the 43 compressor hasassociated therewith a check valve I0 ior preventing back ilow ofcompressed iluid and associated with the outlet of the dome is anothercheck valve II. The pressure tank; 3

is shown as connected by a conduit I2 with a 50 fluid motor I3 which maybe employed to operate any mechanism desired, as for example, a brakingmechanism. The fluid pressure employed to actuate the'l iluid motor iscontrolled by a valve Il in conduit I2, this'valve being shown as a Mhand valve but it is understood thatother valve valve member 23.

mechanisms such as a ioot. control valve may be employed ii.' desired.

In compressors of the type described which are of well-knownconstruction it is desirable to automatically prevent the compressorfrom compress- 5 ing iiuid after the fluid in the receiver has beenplaced under a :predetermined maximum pressure. This is bestaccomplishedjby shutting oi! the intake port so the'air or other uidwhich is being compressed by the lcompressor isnot 10 -permitted toenter the compressing chamber. It

is also desirable that the intake port not only be automatically closedat the proper time but that 1 it also be reopened whenever the pressure.in the receiver drops to a predetermined value below' l5 the saidmaximum.

In accordance with my invention I have pro` vvided an improved valvemechanism I3 which is associated with thecompressor intake and ythecompressor oil dome andthe fluid-pressure o system connected to thepressure tank whereby' the` desired opening and closing of thecompressor -intake is accomplished. The valve mechanism comprisesconnected casings I3 and I1, the former being provided with a bore I3and the latter with two bores I3 and 23. 'The casing I6 is formed withan outlet 2i communicating with the intake port 3 oi.' the compressorwhen the valve mechanism is mounted on the compressor and there `is alsoprovidedv an inlet port 22 (Figure 3)Y lo which is associated withasuitable aircleaner 23. Between outlet 2| and inlet 22 the casing isformed with a valve seat 24I which cooperates vwith a'slidable valvemember 23 positioned in borej|3 and normallybiased oit-its seat by a 35spring. 23 interposed between the valve member and the end ,of the'casing. v'I'he valve member carries on one end an annular rubberelement 21 A,to facilitate tight fitting of the valve member with theseat.` There is alsoa packing. cup 2B o at Athe other end of the valvemember to prevent f leakage of uid past said member.

'I'he valve casing` I'I is secured to lvalve casing I3 by suitable bolts23 (Figure 1)' so that bore I3 is in alignment with bore' I3 of valvecasing 5 I6. The bore I3 communicates by means oi a passage 30 with achamber 3i at the rear ot the This passage is normally closed by a valveelement 32 preventing ilow of iluid from chamber 3| to bore I3.Withinbore 50 I3 is a Vpiston 33 carrying the valvev element 32 by astem 3l, the piston being biased by a'spring 33 to .a position normallyholding "valve element 32 seated. The piston valso carries a valveeiement'- llwhichis adapted toclose passage u Spi in when the piston ismoved to the left and the valve element 32 is unseated. The bore I3 atthe left of the piston is in communication with the atmosphere by ableed passage 31. A packing element 38 seals the piston 33 and the rightend of the bore is connected by a conduit 33 with conduit |2 at a pointbetween the control valve |4 and the uid motor I3.

Within bore 20 of casing |1 is a diaphragm 40 which is normally heldupon a seat 4| by a plunger 42 and spring 43. The diaphragm and seatform a valve to prevent communication between an inlet passage 44connected to the compressor oil dome port of the receiver by a conduit45 and a passage 46 leading to chamber 3| at the lrear of valve member25.

The spring 43 is so designed as to hold the diaphragm against seat 4|until a predetermined pressure is built up in the oil dome and also thepressure tank, which pressure is the maximum pressure desired for thereceiver. When diaphragm is unseated, a larger area will 4:csecl tomaintain it in this position. The g 43 will reseat the diaphragm againstthe pressure in the tank when this pressure drops to a value of aboutten pounds per square inch below the maximum tank pressure. For thepurposes of description of the operation of the valve mechanism, themaximum pressure is considered as one hundred pounds per square inch.The spring 26 which biases the valve member to open position is also sodesigned that it will unseat valve member 25 against the maximum suctioneffect of the compressor and also permit valve member 25 to engage seat24 when fluid pressure is admitted to chamber 3| as a result of thediaphragm 40 being moved off its seat when the pressure in the receiveris one hundred pounds per square inch.

When the valve parts are in the position shown air is free to enter thecompressor and then be forced out into the oil dome and the tank. Whenthe pressure in the oil dome andtank reaches the maximum pressure of onehundred pounds per square inch, the diaphragm 4|) will be moved oil" itsseat, thereby permitting fluid under pressure to flow through passage 46into chamber 3|. This pressure will now move valve member 25 against itsspring 26 to close off communication to the compressor, causing it torun idle. If the control valve |4 should be moved to a position to causeoperation of the iluid motor I3, air under pressure will be admitted toconduit 39 and become effective on piston 33 to move it to the left,thereby unseating valve 32 and seating valve 35. During the shortinterval that the passage 35 is open, the chamber 3| is connected toatmosphere and the pressure in the chamber may drop sumciently to causethe valve member 25 to be unseated by the action of its spring 24.However, as soon as valve element 36 becomes seated, the chamber will beagain closed and pressure from the tank will cause the valve member 25to be quickly reseated.

If operation of the fluid motor causes the air pressure in tank 8 todrop more than ten pounds per square inch, the diaphragm 40 will beforced onto its seat 4| by spring 43 so that iiuid under pressure nolonger can enter chamber 3|. When the control valve |4 exhausts thefluid pressure in the fluid motor, fluid pressure acting on piston 33will also be exhausted and the piston, under the action of the lightspring 35, will be forced to the right, rst unseating valve element 36and then, after a short interval, reseating valve element 32. Duringthis short interval between the unseating of valve element 33 andreseating of valve element 32, the chamber 3| will be in communicationwith the atmosphere .by way of passages 30 and 3l, thereby relieving thehigh pressure in chamber 3|. The amount of uid to be exhausted fromchamber 3| is very small and although the interval between the unseatingof valve element 36 and reseating ofvalve element 32 may be short,passageway 30 is, nevertheless, open long enough to permit a substantialdrop in the pressure of the fluid in the chamber 3|. Furthermore, thefluid pressure acting on piston 33 will never be exhausted quickly dueto the fact that it must pass back through pipe 33 and out through thecontrol valve I4 along with the fluid being exhausted from the fluidmotor |3 and this will also aid maintaining the passage 3l open longenough to cause a sufficient drop in pressure in chamber 3|. The drop inpressure in the chamber permits spring 23 to force the valve member 25away from seat 24 and again allow air to flow to the intake of thecompressor. The compressor will now operate until the one hundred poundsper square inch pressure in the dome and tank is reached when the valvemember will again close off the compressor intake in a manner alreadydescribed.

If during operation of the fluid motor I3 the drop in air pressure inthe tank 8 is less than ten pounds per square inch, then the diaphragm40 will not be seated by the action of spring 43 and chamber 3| will notbe disconnected from the air tank. Under these conditions when thecontrol valve |4 exhausts the pressure in the fluid motor, the airpressure in chamber 3| will be relieved to atmosphere during theunseating of valve element 36 and the reseating of valve element 32 andpossibly some fluid will also escape from the air tank due to thediaphragm 40 being unseated. 'Ihe drop in pressure in chamber 3| willsuflicient to permit the spring 26 to move valve 25 off seat 24 and openthe intake of the compressor. However, as soon as valve 32 becomesseated, fluid under pressure will again be built up in chamber 3| andthe valve element 25 reseated. This momentary opening and reclosing ofthe intake valve, however, does not interfere with the desired operationof the valve control mechanism and the maintaining of the pressure intank 8 within predetermined limits.

In order to insure that the air pressure in chamber 3| will besufliciently released to allow valve member 25 to be unseated by spring25, there is provided a small bleed ypassage 41 through the valve memberwhich in the construction shown is approximately one forty-thousandthsof an inch in diameter. This small bleed passage will not affect theclosing action of the valve member since it is of such size thatpressure can be built up in chamber 3| to move the valve member, Afterthe valve member has become seated what little leakage of fluid takesplace through the bleed passage enters into the intake oi' thecompressor and is again placed in the dome.

In the event there should be a leak in the compressor dome or the tankwhich may cause a drop in the pressure in the dome or tank or both whilethe compressor is shut off and during the period that the fluid motor I3is not operated, the valve mechanism, nevertheless, will function toopen the intake of the compressor. For example, if the drop should beten pounds per square inch,

this would be sufficient to permit diaphragm 43 JI t andasse to engageseat Il. No additional pressure will now be placed in chamber-ll and,therefore, the pressure therein will drop because of bleed passage 41.When the pressure in chamber 3| drops to such a value that the springcan move valve element 2B to open position, the compressor will againIbegin to operate and bring the pressure in l the dome and the tank' upto its maximum value at which point the valve mechanismv willv againl 1. In apparatus of the class described, a fluid u to the receiver,pressure-operated valve means compressor provided with an intake portand an exhaust port, a fluid pressure receiver connected to the exhaustport, a iluid pressure-actuated system adapted to be operated by uidpressure from the receiver, a casing having a passage in coml municationwith the intake port, a chamber in the casing, a movable valve member inthe chamber and adapted to control the passage, a spring for biasing thevalve member to open position, conduit means for' connecting the chamberto the receiver, pressure-operated valve means for permitting uid toflow to the chamber when the pressure in the receiver is a predeterminedvalue,y

means forming a relief passage from the chamber,

and valve means independent of the pressure-- operated valve means andoperable by fluid pressure from the fluid-actuating system for causing arelease of the fluid under pressure in the chaml ated system adapted `tobe operated by uid` pressure from the receiver, a casing having apassage in communication with the intake port, a chamber in the casing,a movable valve member in the.

chamber and adapted to control the passage, a spring for biasing thevalve member 'to open position, conduit means vfor connecting thechamber to the receiver, pressure-operated valve means for permittingiiuid to flow to the chamber when i the pressure in the receiver isapredetermined value, means forming a relief passage from the chamber,and spring-biased -valve means operable` by iiuid pressure from thefluid pressure-actuated system for controlling said valve means, saidvalve means being so associated with the relief passage *hat operationthereof by fluid pressure will first open the passage then close it andrelease of the pressure will permit reopening of the passage and then aclosing thereof under the action of the spring.

compressor'provided with an intake port and an exhaust port, a fluidpressure receiver connected to the exhaust port, a uid pressure-actuatedsystem adapted to be operated by fluid pressure` from the receiver, vacasing having'a passage in communication with the intake port, a chamberin the casing, a movable valve member in the"v chamber and adapted tocontrol the passage, a

spring for biasing the valve member to open position, conduit means forconnecting the chamber for permitting fluid to flow to the chamber whenthe pressure in the receiver is a predetermined value, and means forminga restricted relief passage through the movable valve member and placingthe chamber in constant communication with the portion of the passage inthe casing which constantly communicates with the intake when thepassage is closed. L

4. In apparatus of the class described, a fluid i compressor providedwith an intake port .and van exhaust port, a fluid pressurereceiverconnected to the exhaust port,v a casing having a passage incommunication with the intake port,

. a chamber in thecasing, a movable valve member in the chamberv andadapted to control the passage, a spring for'bia'sing the valve membertoopen position, conduit means for vconnecting the f chamber to thereceiver, and pressure-operated valve means for permitting fluid toflow-to the chamber when the pressure in the receiver isa predeterminedvalue, said valve 'means comprising a seat associated with the conduitmeans, a- I flexible diaphragm and a spring member for blasing thediaphragm against the seat,.and means including, a restricted passagefor placing .the chamber in communication with the intake only of thecompressor lwhen the valve member is in closed position.

5. In apparatus of the class described, 'a fluid compressorprovided withan intake port land an exhaust port, a fluid pressure receiver"connected to the exhaust port, a casing having a passage incommunication with the intake port, a chamber in the casing, a movablevalve member in the chamber vand adapted to control the passage, aspring orbiasing the valve member to open position, conduit means forconnecting the l chamberto the receiver, pressure-operated valve meansfor permitting fluid to flow tothe chamber when thepressure in thereceiver is a predetervmined value, said valve "means comprisinga seat*associated with the conduitmeans, a flexible `diaphragm and a springmemberI for biasing the diaphragm against the seat, and means forrelieving the pressure in the chamber.

6. In apparatus of the class described, a fluid compressor provided,with an intakev port and an exhaust port, afluid pressure receiverconnectedv tothe exhaust'port, a uid pressure-actuated system adapted tobe operated by uid pressure from the receiver, a casing structurlavingtwo communicating aligned boresand a third bore,-means including aportion of one of. the aligned b'ores for forming a passagecommunicating-with the intake of the compressor, la movable valve memberin said'last `named bore for controllingthe passagea spring for biasingthe valve vmember to open position, conduit means for placing the thirdbore in communication with the bore having the movable valve member andat a point to the rear thereof, means for connecting the third bore'with the receiver, valve means associated with the third bore forpreventing iluid 3. In apparatus of the class described, a fluid lastvnamed valve means and comprising a movable member in the other of thealigned bores.

'7. In apparatus of the class described, a iluid compressor providedwith an intake port and an exhaust port,` a iluid pressure receiverconnected to the exhaust port, av fluid pressure-actuated system adaptedto be operated by uid pressure from the receiver, a casing having apassage in communication with the intake'port, a chamber in the casing,a movable valve member in the chamber and adapted to control thepassage, a spring for biasing the valve member to open position, conduitmeans for connecting the chamber to the receiver, means forming a reliefpassage from the chamber, valve means for controlling the relief passageand comprising a movable member having a. valve stem carrying spacedvalve

